The present invention is directed to the field of marine propulsion. More particularly, the present invention is directed to a protective waterproof floatation case for a marine propulsion unit such as an outboard motor deployed from a submarine, or the like, enabling the motor to float without shooting to the surface like a cork, endangering any personnel in the vicinity or monitoring its deployment. It is a further advantage of the waterproof case of the present invention that this case enables the motor to be suspended from the transom and operated without the need to completely remove the case. Lastly, two-way valves allow the case to evacuated of corrosive fluids such as residual fuel and vapors which could otherwise destroy plastic parts of the motor disabling the propulsion unit.
In covert military operations, and the like, personnel are deployed from a submarine with an inflatable raft and an outboard motor which is attached/attachable to the raft. The motor must be small enough to be ejected from a through-port such as a torpedo bay. The 30 HP Evinrude multi-fuel engine has proven suitable for this application. To protect the outboard motor, the engine needs to be encased in a waterproof case.
Problems with existing encasements include lack of durability. Existing systems are easily torn exposing the engine to ingestion of water (probably saline) which can lead to inoperability of the motor and exposing the military personnel to danger topside on an immobile floating platform. Further problems with existing cases include subsequent storage. Residual fuel in the engine leaks into the compartment formed by the case and is corrosive to plastic parts in the engine resulting in an inoperative motor which is, accordingly, useful only as a paperweight.
A second set of problems associated with existing cases has to deal with their size. Since, generally, the cases are not tailored to fit a particular motor, they are significantly larger than they need to be. Even when cases have been made with particular motors in mind, they typically are not snugged up around the motor. These oversized cases may prevent the package from fitting through the limited-sized space available such that the motor cannot be deployed at all from the through-port or frequently gets stuck requiring excessive effort to eject it from the vessel.
In addition, these oversized cases entrap a great deal of air such that the package is not easily made neutrally buoyant, requiring in excess of 400 lbs. in weights to be added. These rapidly rising packages shoot like corks dozens of feet into the air. Such a projectile imposes a hazard to the personnel deployed with the raft and the impact upon returning to the surface of the water may damage the package, either the casing or the motor itself. The rapidly rising package can present a problem for the deployed personnel to keep up with. If they succeed in rising at the same rate as the engine, they may experience an arterial gas embolism (AGE).
Lastly, and perhaps most importantly, once the encased motor reaches the surface, the bag must be removed from the motor to enable it to be mounted on the transom of the inflatable raft. These covert operations are typically performed in the dead of night and removing the case and mounting the motor is problematic in calm seas and, should the weather refuse to cooperate, the military personnel tasked with the problem frequently lose their grip and the unclad motor plunges into the water threatening to disable the engine. It is among the features of the present invention to permit the motor to be mounted on the transom securely and the case taken out of the way without requiring total removal, thereby allowing the team to get underway in a significantly shorter time than is possible with existing cases. This can be critical, not only to the success of the mission but to the survival of the military personnel, given that while attempting to deploy the watercraft, the team is essentially a flock of sitting ducks.
It is among the objects of the present invention to overcome the problems associated with the prior art cases. The waterproof case of the present invention is tailor-made for the 30 HP Evinrude multi-fuel engine (MFE), the motor which is frequently deployed in these covert military operations. It will be appreciated that the features of the present invention could be configured to house a different engine without departing from the particulars of the invention. This vulcanized skin-tight case has a plurality of valves, several one-way “exhaling” valves which permit air to be expelled from the interior but no air (or water) allowed in. A separate two-way valve is provided which will allow re-inflation once the package has reached the surface. The case of the present invention increases the dimensions of the engine cover by no more than ½″ in any direction. The volume of the case housing the motor is reduced by more than 50% from 14 ft3 to 6.9 ft3. This slim package can more easily be guided through the 30″ diameter torpedo bay than prior art encased motors. Further, the waterproof case of the present invention is neutrally buoyant to 50 FSW (feet of sea water). To make one of the prior art cases neutrally buoyant to 50 FSW would require over 400 lbs of lead weight. That compares to roughly 120 lbs with the bag of the present invention.
The material used in constructing this case is a nylon mesh fabric coated with a Neoprene® elastomer to create a fabric having a weight of 60 oz per square yard. This fabric has a breaking strength of 1000 psi. The vulcanization process used for glue-free assembly has had no history of delamination in the over 30 years since its development. Additional reinforcement is provided in areas where additional strength is needed, i.e., where the unit is attached to the transom (which can be effected prior to deployment, if desired), and in the areas of the propeller and gear box. This reinforcement is preferably supplied by doubling the thickness of the skin in those areas of concern.
The present invention consists of a waterproof floatation case for an outboard motor including a) a left side panel constructed of waterproof material and having a first edge; b) a right side panel constructed of waterproof material and having a first edge, said first edge of the right side panel being common to the first edge of the left side panel; c) a waterproof zipper extending at least 180° about a peripheral extent a second edge of the left side panel and a second edge of the right side panel of the waterproof floatation case, the peripheral extent including the first and second common edges; whereby an outboard motor fully encased in said waterproof floatation case may be discharged from a submarine, mounted on a transom of an inflatable watercraft, the waterproof zipper moved to a disengaged position and the left side butterflied with a bungee and the right side butterflied with a second bungee allowing the outboard motor to be operated without having the waterproof floatation case fully removed from the outboard motor.
Preferably, the waterproof material from which the left panel and the right panel are constructed is nylon mesh fabric to which an elastomer is secured. More preferably, the elastomer comprises a neoprene secured to the nylon mesh fabric by vulcanization. The case preferably includes at least a single one-way valve permitting the waterproof floatation case to off-gas excessive atmospheric pressure when exposed to subsurface conditions. More preferably, the at least a single one-way valve comprises a plurality of one-way valves. In addition, a two-way valve is positioned atop the waterproof floatation case permitting influx and efflux of air to and from the waterproof floatation case. Further, reinforcement means is situated within the waterproof floatation case in areas of concern for potential puncture, those regions including the area where the outboard motor attaches to a transom of the watercraft, adjacent a gear box of the motor and in a vicinity of a prop.
A second aspect of the present invention is directed to a method of deploying a watercraft for covert military operations, and the like, comprising the steps of a) encasing a propulsion unit in a waterproof case, the waterproof case having a zipper which extends at least 180° about a vertical periphery of the case; b) deploying the watercraft from a subsurface vessel, the watercraft including an inflatable raft and the encased propulsion unit; c) mounting the encased propulsion unit on a transom of the inflated raft; d) disengaging the zipper to partially reveal the propulsion unit; e) butterflying a left panel of the waterproof case on a first side of the propulsion unit and securing the left panel of the butterflied case in a first position enabling operation of the propulsion unit; f) butterflying a right panel of the waterproof case on a second side of the propulsion unit and securing the right panel of the butterflied case in a second position enabling operation of the propulsion unit without the necessity of completely removing the waterproof case.
Yet a third aspect of the present invention involves a method of encasing a propulsion unit of a watercraft following a covert military operation comprising the steps of a) releasing a first bungee securing a right panel of a waterproof case from its position secured adjacent a right side of the propulsion unit; b) releasing a second bungee securing a left panel of a waterproof case from its position secured adjacent a left side of the propulsion unit; c) reconfiguring the waterproof case to surround the propulsion unit; d) re-engaging a waterproof zipper which extends at least 180° about a vertically oriented periphery of the propulsion unit, a first half of which zipper extends along a first edge of the right panel and a second half of which zipper extends along a first edge of the left panel to form a waterproof enclosure for the propulsion unit; e) pulling suction on the waterproof enclosure to evacuate corrosive fluids from an interior portion of the enclosure prior to storing the encased propulsion unit.
Various other features, advantages, and characteristics of the present invention will become apparent after a reading of the following detailed description.